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! d i g i t a l ! I N T E R O F F I C E M E M O R A N D U M
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To: KL-10 Front-End Group
Date: 6 Aug 75
From: Tom Porcher
Dept: DEC10 S.E. Dept.
Loc: MR1-2 Ext: 6788
File: [DOC-FRONT-END]
LP.SPC
Subj: LP-20 Driver Functional Specification
This functional specification describes the interface to the
LP-20 from the KL-10 front end monitor, RSX10-F. The special
features of the LP-20 are described in the design spec for said
device, and are not described herein.
INTER-PROCESSOR COMMUNICATION
All communication between the -10 and the LP-20 driver goes
through the DTE-20, using the queued protocol. the following
is a list of the available functions to tthe LP-20.
From -10 Information
Code Function
3 String Data
This function addresses a specific line-printer and is
data to be printed. The request is queued to the
proper line-printer and the line-printer is started.
5 Return Device Status
The current device status is sent to the -10. See
below, Send Device Status
11 Flush Device Output
This clears any I/O that is in progress on the
specified line-printer, and clears the request queue.
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SUBJ: LP-20 Driver Functional Specification
7 Here is Device Status
The LP-20 specific operations are handled as
subfunctions of this function. The function specifies
the line-printer to perform the function for, and the
length of the function block. This is similar to
string data, except that the data is interpreted by the
driver and not sent to the LP-20. The first word of
the function data is the function code. The following
are the functions available:
Code Subfunction
129 Load LP-20
This function has one argument: the name of
the file on the RSX-10F File System to load.
This file contains the Vertical Format and
Translation RAM. Blocks 1, 2 and 3 are
ignored. Block 4 is the Translation RAM. The
first word of block 5 gives the length of the
VF (in bytes), which is the rest of the file.
These files are set up for the proper
processing of the data sent to the LP-20.
130 Set Page Counter Interrupt
The low-order 12 bits (bits 11-0) of the
argument are the value to be set in the page
counter. Bit 15 is set to enable page count
zero interrupts, clear to disable.
131 Set device status register.
This function allows the -10 program to set or
clear the DELHLD and MODE bits in the LP-20
Status Register. This is to allow for testing
of the printer, as well as special character
functions.
2 Continue
There are no arguments to this function. If
the specified line-printer is stopped, due to
an error, illegal character interrupt, or page
count reaching zero, the LP-20 output is
resumed.
1 End-of-File
This clears the checksum, and also sends the
device status.
TO: KL-10 Front-End Group Page 3
SUBJ: LP-20 Driver Functional Specification
To -10 Information
Code Function
15 Acknowledgement
This is sent whenever there is room for more data to be
sent to the LP-20. The transmission of this function
to the -10 indicates that the -10 can send more data.
7 Here is Device Status
This is sent on request from the -10, or when the LP-20
stops for an error. It is also sent if the LP-20 comes
on-line. Page count reaching zero will only stop and
send status if it is enabled, by bit 15 of the Set Page
Count function.
The format of the status information sent is as follows:
Word 0 (byte 0) Current state:
-5 Device error wait
-4 VFU error wait
-3 Page count zero wait
-2 Illegal character wait
-1 LP-20 off-line (I/O in progress)
0 LP-20 off-line (device idle)
1 I/O in progress
2 Device idle
Word 0 (byte 1) Accumulated Checksum
LP-20 Device Registers:
Word 1 LPCSRA
Word 2 LPCSRB
Word 3 LPBSAD
Word 4 LPBCTR
Word 5 LPPCTR
Word 6 LPRAMD
Word 7 LPCBUF/LPCCTR
Word 8 LPCKSM/LPTDAT
TO: KL-10 Front-End Group Page 4
SUBJ: LP-20 Driver Functional Specification
QUEUE I/O INTERFACE
All data sent to the LP-20 from tasks running in the -11 are
sent via the QUEUE I/O directives. The LP-20 Driver accepts
the following I/O functions
IO.WLB Write Logical Block. Data is entered into the threaded
output queue for the specified LP.
IO.WVB Write Virtual Block. Same as IO.WLB
IO.KIL Kill all pending requests. Aborts all sending QUEUE
I/O requests to the specified LP with I/O status IE.ABO
(Operation Aborted).
IO.ATT Attach Device. Ignored.
IO.DET Detach Device. Ignored.
All other functions return IE.IFC (Illegal Function Code).
The following I/O status returns are given by the LP-20 Driver
for a request:
IS.SUC Successful Completion. Data has been printed.
IE.DNR Device Not Ready. The VFU has encountered an error
when printing.
IE.VER Controller Error. A non-recoverable error has occured
(i.e., parity error).
IE.ABO Operation Aborted. Output has been flushed due to an
IO.KIL request or a flush device request from the -10.
IE.IFC Illegal Function Code. The specified I/O function is
not one of the set IO.WLB, IO.WVB, IO.KIL, IO.ATT or
IO.DET.
All device error conditions cause a message to be printed on
the console. Any error except off-line aborts the request,
while off-line waits for on-line.
PROGRAM FUNCTIONAL DESCRIPTION
The LP-20 Driver is broken up into several modules:
LPDATA Common Database and Parameters
LPTASK Task-Level Service
LPINT LP-20 Interrupt Service Routine
LPCOMM Common Subroutines
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SUBJ: LP-20 Driver Functional Specification
COMMON DATABASE AND PARAMETERS
The number of LP-20's the driver is to service is the value of
the symbol LPNUM.
All device-specific (i.e. for each LP) data is kept in the
device status block for each device. This is a table LPTBL
which has an 8-byte block for each LP, starting with unit 0.
Throughout the driver, the address of the block for the current
LP is kept in R2. The size of each entry (8 bytes) is the
value of the symbol LPSIZE.
LPTBL descriptions:
0 LPTHD Pointer to threaded output list. This is the
address of the first item in the list (next to
be printed), zero if there is no list.
2 LPEXP External Page Adddress for this LP. This is
the starting address of the device registers
for this device (i.e., the address of LPCSRA).
This is normally kept in R3 when it is needed.
4 LPSTS Status bits:
LP.HNG Device hung. This bit is set every 20
seconds when the LP is not idle, and if
it is not cleared in the next 20
seconds (by doing output) the LP is
assumed to be hung. The LP is started
going again.
LP.SST Send status to -10. This bit is set
whenever a change in status (i.e.,
off-line) requires the -10 to be
notified. It is set at interrupt
level, and checked at task level.
LP.WAT Device is waiting for -10 to respond.
This occurs on enabled interrupts (page
count reaching zero, illegal character,
or controller error).
LP.PZI Page count zero interrupt enable. This
bit being set causes output to stop and
wait for a response from the -10 when
the page count register reaches 0.
LP.MCH Multi-character print. This bit is set
when a multiple-character print
sequence (i.e., 'arrow" mode) is in
progress. This indicates that DONE
being set means to continue the current
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SUBJ: LP-20 Driver Functional Specification
buffer after the character which caused
the multi-character print.
LP.LDF Load Load File. Set by interrupt
service if VFUERR is up before starting
a transfer or on encountering a Load
File function in the threaded list.
File is loaded at task level.
LP.LIP Load in progress. Set by task on
starting load, cleared by interrupt
service when a Set Mode 0 (Normal mode)
function is encountered.
LP.F10 From -10 request. Set on any -10
request (data, status or function).
Cleared when threaded output list is
emptied. Used to determine if status
and acknowledgements should be sent to
the -10.
LP.EOF End of File. Set when End of File
function encountered by interrupt
service by ..SSLP when checksum is
cleared.
LP.UNT (Bits 1 and 0). Unit number of this
LP.
6 LPITH Interrupt-level thread pointer. This points to
the thread block in the threaded list which is
currently being output. Zero if the LP is
stopped or idle.
A parallel table, LPTBL2, has additional information. Again,
the entry for each LP is 8 bytes long. The indexes into LPTBL2
are defined from the start of LPTBL, so that the same pointer
(usually in R2) can be used for both tables. The contents of
this table:
0 LPMCB Multi-character buffer. This word is a 2-byte
buffer for multi-character print operations
(i.e. 'arrow' mode).
2 LPCSM Accumulated Checksum (low byte). Cleared by
End of File function from -10. High byte is
trash.
4 LPFID File-ID of last file loaded to LP-20
6 LPFSQ File-sequence number of last file loaded to
LP-20.
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SUBJ: LP-20 Driver Functional Specification
Another parallel table, LPTBLS, has more information.
0 LPFIL (4 words) Filename and extension of file to
load from -11 file system.
Threaded Output List
All output to each LP is kept in a threaded output queue. The
current head of this queue is kept in LPTHD for each LP. Each
thread block has the following information:
0 T.HRED Thread word. Points to next thread block in
list. Zero if end of list.
2 T.HBCT Byte count of thread block and following data,
if any. This value is used to return the
thread block to the free pool. If this word is
zero, it is a Queue I/O request, and it is an
extended thread block (length T.HQRS) which has
more stuff in it. See definitons below.
4 T.HCAD Address of data to be printed (physical). If
this is zero, this is not a data request, but a
special function request. See definitions
below.
6 T.CBC Byte count of data. If this is negative, the
data has been sent (or function completed).
This may be zero.
The size of this thread block is T.HHDS, 8 bytes.
Queue I/O request thread blocks have the following additional
information:
10 T.HEMA Extended Memory address bits. Bits 5 and 4 are
the memory extension bits, bus address bits 17
and 1 respectively. In all other requests
these bits are zero.
12 T.HNAD Address of Queue I/O request node which invoked
this request. This is needed to complete the
Queue I/O request and tell the requesting task
that his I/O has been done.
The length of this Queue I/O request thread block is T.HQRS, 12
bytes.
Special function thread block entries (T.HCAD zero) specify the
function to be performed in the byte count word T.HCBC. The
arguments to the function follow the thread block, at
T.HHDS+nn.
TO: KL-10 Front-End Group Page 8
SUBJ: LP-20 Driver Functional Specification
The following functions are implemented:
Code Function
131 Set or clear DELHLD or MODE bits in LP Status Register
LPCSRA. The argument is the new bits, in the proper
positions. Note that setting mode 0 (normal) clears
LP.LIP (Load File complete).
130 Set Page Count in LPPCTR. The argument is the value to
set it to.
129 Load File. Sets LP.LDF and I/O Done to tell task to
load Load File.
1 End of File. Clears Checksum and sends current status
to -10.
TASK LEVEL CODE
Upon initialization, the LP driver task must first enable for
Mark-Time interrupts every 20 seconds (for hung check). The
address of the task's event flags (A.EF of the task header) is
also saved so that the interrupt-level routine can set the I/O
done flag EF.LPD. The LP is reset.
After initialization, the task routine waits for someting to
do, indicated by an event flag coming up. The event flags
waited for are EF.LPD (interrupt-level I/O done), EF.NIR (Queue
I/O request), and EF.LPC (Mark-Time request, every 10 seconds).
They are cleared and checked in that order.
Interrupt-level I/O done (EF.LPD)
LPIOD is dispatched to whenever the event flag EF.LPD is set.
This is set by the interrupt service when it has completed
transmission of a buffer, or requires the status of an LP to be
sent to the -10 (because of error or such).
Each LP's threaded output list is scanned for 'done' buffers
(indicated by a negative byte count T.HCBC). These are
returned to the free pool, and, in the case of Queue I/O
requests, ..IODN is called to tell the requestor that his I/O
has been successfully completed. If a Queue I/O request is
stopped in the middle of a transfer (for error, page count
zero, etc.), an error indication is given to ..IODN, and the
transfer is aborted. LP.WAT is cleared and the next buffer (if
any) is started.
After the scan of the threaded list, the status of the LP is
sent to the -10 (by calling ..SSTSLP) if the LP.SST flag was
set by the interrupt service. If data is to be printed, the
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SUBJ: LP-20 Driver Functional Specification
output is started by calling TESTLP. If a buffer was
completed, and the last buffer has been started, or there is
nothing left in the list, a request to send more data is sent
to the -10 by calling ..SACK.
Queue I/O requests (EF.NIR)
LPNIR is dispatched to when the event flag EF.NIR is set. This
occurs whenever another task has requested output on any LP.
All LP's are checked for requests by calling ..DQRN (dequeue
request node), which fails if there is no request.
The request is queued up in the threaded output list for this
LP, using an extended thread block. This block is
distinguished as a Queue I/o request by the header byte count
T.HBCT being zero (the actual length is T.HQRS). The
additional information in this thread block is:
T.HEMA Extended memory address bits. Bits 5 and 4
represent bits 17 and 16 of the physical
address of the data to be sent.
T.HNAD Address of Queue I/O request node which invoked
this data request. This is to allow completion
of the request and notification to the
requestor that his output has been completed.
Mark-Time requests every 10 seconds (EF.LPC)
LPMKT is dispatched to every time the event flag EF.LPC is set,
which should be every 10 seconds, as requested. This is the
hung checking routine.
An LP is assumed to be hung if it has I/O in progress
(indicated by LPITH non-zero) and the flag LP.HNG has not been
cleared by starting another buffer (..DOLP routine). If the LP
is hung, and DONE is set, the next buffer in sequence is
started. If DONE is not set, output is resumed by setting GO.
The LPHUNG counter is incremented, for debugging purposes.
In any case, if I/O is in progress, the LP.HNG flag is set so
that it can be checked in another 10 seconds.
SSTSLP Send Status to -10.
This routine is called to send the current status of the
specified LP to the -10 in the format described above. It is
called from task level, either from the LP task or the DTE
task, in request for status from the -10 or a change in status
of the LP.
TO: KL-10 Front-End Group Page 10
SUBJ: LP-20 Driver Functional Specification
The following is the algorithm used to determine the current
state value for the LP.
1. If the LP has data to be printed (LPTHD non-zero), go
to step 2. Otherwise, return 2 if LP is on-line, 0 if
not.
2. If the LP is in a wait state, indicated by LP.WAT being
set, go to step 4. If the LP is off-line, go to step
3. Otherwise, the LP is on-line, I/O in progress, so
return 1.
3. LP off-line, I/O in progress, so return -1.
4. LP waiting. If PAGZRO is set, return -2. If UNDCHR is
set, return -3. If VFUERR is set, return -4 otherwise
return -5 for all other errors.
The status block is then sent to the -10 if LP.F10 (from -10
request) is set. Otherwise, error conditions (state code
negative) cause an error message to be printed on the console.
Call:
R2 -- Pointer to LPTBL entry for this LP.
Return:
R1 -- State code
TESTLP Start LP-20 on threaded list if ready
This routine is called to start the LP-20 if it is on-line and
data is to be printed. This is called from the I/O DONE
service. If the VFU needs to be reloaded, as indicated by
LP.LDF or VFUERR being up, the Load File is loaded by calling
LOADLP. The LP is started by calling..DOLP.
INTERRUPT SERVICE ROUTINE
$LPINT is the interrupt service routine for all LP's. The unit
number of the interrupting LP is stored in the low-order bits
of the PS, the condition codes, when $LPINT is called. All
used registers are saved.
If the interrupting LP is idle, the status of the LP is sent to
the -10 by setting LP.SST. This is incase the LP just came
on-line.
If the LP has I/O in progress, the checksum is accumulated and
the following conditions are checked. Note that if I/O is
stopped for any reason, the currrent byte count and data
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SUBJ: LP-20 Driver Functional Specification
address are stored back in the thread block, in T.HCBC and
T.HCAD repectively.
Undefined character
IF the UNDCHR bit is set in LPCSRA, this indicates that
processing is required on this character. The RAM data for
this character is used to determine the course of action. If
the RAM data is less than 100 (octal), I/O is stopped and the
status is sent to the -10, waiting for a response from the -10.
If the RAM data is greater than or equal to 100, the RAM data,
preceded by an up-arrow, is printed. This is accomplished by
storing the up-arrow and the RAM data in the multi-character
echo buffer LPMCB and starting output there. The flag LP.MCH
is set so that the next time DONE comes up, the current buffer
is resumed.
Page count reached zero
If the PAGZRO bit is up, the page count has been decremented to
zero. If the page zero interrupt flag LP.PZI is set the status
is sent to the -10, and waits for a response from the -10.
Otherwise, PAGZRO is cleared by clearing the page counter and
the current buffer is resumed by caling..DOLP.
Error
Any errors stop I/O and send status to -10, but just off-line
does not require a response from the -10 to continue. Any
other error sets the flag LP.WAT to indicate wait for a
response. Note that the error bit is cleared when the status
is sent at task level by the ..SSLP routine. VFU errors
require the vfu to be reloaded.
Done
When DONE comes up, the next buffer in the threaded list is
started, and the current buffer marked as done by setting the
byte count word T.HCBC to a negative number. The event flag
EF.LPD is set to indicate to the task that a buffer has been
completed.
However if this DONE interrupt is during a multi-character
print operation (i.e. 'arrow' mode), the current buffer is
just continued where it was left off.
TO: KL-10 Front-End Group Page 12
SUBJ: LP-20 Driver Functional Specification
COMMON SUBROUTINES
These routines are called from the LP driver task, other tasks
(mostly DTE task), and from the interrupt service routine.
These are kept in core, with the system common subroutines.
..STLP Start LP-20 Output
This routine is called only from the Queued Protocol Task with
a thread block to be output. The Function code is in the high
byte of T-HCBC, and the subfunction code or byte count of data
is in the low byte. ..PTLP is called to queue the thread block
up in the threaded list.
Call:
R0 -- Address of thread block.
R2 -- Pointer to LPTBL entry for this LP.
Return:
No registers modified
..PTLP Put thread block in threaded output list
This is a task-level routine to enter a thread block into the
end of the threaded output list, and start the LP going if it
is idle. The thread block is assumed to be the new end of the
list, so the thread word of this block is cleared. Note that
task-switching must be inhibited when the thread block is being
entered in the list.
Call:
R0 -- Address of thread block to be added to list and
output.
R2 -- Pointer to LPTBL entry for this LP.
Return:
No registers modified.
TO: KL-10 Front-End Group Page 13
SUBJ: LP-20 Driver Functional Specification
..SPLP Stop LP-20 Output
This is a task-level routine to flush all output to the
specified LP. The LP is reset by setting RSTERR. All the
active thread blocks in the threaded output list are marked as
DONE by setting T.HCBC negative (just bit 15 on). The Queue
I/O requests are given IE.ABO by the LP task when the list is
scanned.
Call:
R2 -- Pointer to LPTBL entry for this LP.
Return:
No registers modified.
..DOLP Initiate LP-20 Transfer.
This is an interrupt-level routine to start the LP specified on
a specific entry in the threaded list.
If the thread word specified to start is zero, nothing is done
and the LP is left idle.
If the data address T.HCAD is zero, this is a special function
so it is performed. The function code is taken from the byte
count word T.HCBC and the arguments to the function follow the
thread block at T.HHDS+nn. See the thread block definitions
above for a description of the functions available. After the
function is performed, the next buffer in the threaded list is
started.
Otherwise, the data is started to the printer via DMA, by
setting up the byte count LPBCTR, bus address LPBSAD, and the
extended memory bits 16 and 17 in LPCSRA. The transfer is
initiated by setting GO, INTENB, and PARENB.
This routine may be entered at ..DOL1 to start the next buffer
in sequence, unless LP.MCH is set, in which case the current
buffer is resumed. This is normally called when DONE is set.
In any case, the flags LP.HNG, LP.WAT, and LP.MCH are cleared.
Call:
R0 -- Address of thread block to start output at.
May be zero if this is end of threaded list.
R2 -- Pointer to LPTBL entry for this LP.
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SUBJ: LP-20 Driver Functional Specification
R3 -- External Page address of this LP (address of
LPCSRA).
Return:
R0 -- Address of current thread block being output.
[End of LP.SPC]